1. Field of the Invention
Exemplary aspects of the present invention relate to a fixing device, an image forming apparatus, and a fixing method, and more particularly, to a fixing device for fixing a toner image on a recording medium, an image forming apparatus including the fixing device, and a fixing method for fixing a toner image on a recording medium.
2. Description of the Related Art
Related-art image forming apparatuses, such as copiers, facsimile machines, printers, or multifunction printers having at least one of copying, printing, scanning, and facsimile functions, typically form an image on a recording medium according to image data. Thus, for example, a charger uniformly charges a surface of an image carrier; an optical writer emits a light beam onto the charged surface of the image carrier to form an electrostatic latent image on the image carrier according to the image data; a development device supplies toner to the electrostatic latent image formed on the image carrier to make the electrostatic latent image visible as a toner image; the toner image is directly transferred from the image carrier onto a recording medium or is indirectly transferred from the image carrier onto a recording medium via an intermediate transfer member; a cleaner then cleans the surface of the image carrier after the toner image is transferred from the image carrier onto the recording medium; finally, a fixing device applies heat and pressure to the recording medium bearing the toner image to fix the toner image on the recording medium, thus forming the image on the recording medium.
Such fixing device may include a cylindrical-shaped metal member to heat the fixing device effectively to shorten a warm-up time or a time to first print (hereinafter also “first print time”). Specifically, the metal member provided inside a loop formed by an endless fixing belt and facing the inner circumferential surface of the fixing belt is heated by an internal heater so as to heat the fixing belt. A pressing roller presses against the outer circumferential surface of the fixing belt to form a nip between the fixing belt and the pressing roller over which the recording medium bearing the toner image passes. As the recording medium bearing the toner image passes through the nip, the fixing belt and the pressing roller apply heat and pressure to the recording medium to fix the toner image on the recording medium.
While the fixing belt rotates in accordance with rotation of the pressing roller, the fixing belt slides over the stationary metal member, generating friction between the fixing belt and the metal member and resulting in wear of the fixing belt. To address this problem, a lubricant may be applied between the fixing belt and the metal member. However, the lubricant is heated by the metal member and volatilized. Thereafter, the lubricant is leaked from a gap between lateral edges of the fixing belt and the metal member. Accordingly, the lubricant is reduced over time, and therefore is not provided between the fixing belt and the metal member in an amount sufficient to prevent wear of the fixing belt sliding over the metal member.